Upgrade to Disprosium-M1

Closes gh-22930

build.gradle

@@ -39,7 +39,7 @@ ext {
 	kotlinVersion        = "1.3.31"
 	log4jVersion         = "2.11.2"
 	nettyVersion         = "4.1.36.Final"
-	reactorVersion       = "Dysprosium-BUILD-SNAPSHOT"
+	reactorVersion       = "Dysprosium-M1"
 	rxjavaVersion        = "1.3.8"
 	rxjavaAdapterVersion = "1.2.1"
 	rxjava2Version       = "2.2.8"
@@ -148,7 +148,7 @@ configure(allprojects) { project ->
 
 	repositories {
 		maven { url "https://repo.spring.io/libs-release" }
-		maven { url "https://repo.spring.io/snapshot" } // Reactor
+		maven { url "https://repo.spring.io/milestone" } // Reactor
 		maven { url "https://oss.jfrog.org/artifactory/libs-snapshot" } // RSocket
 		mavenLocal()
 	}